changed an iPhone battery

these lines I decided to check on 4 DeWalt 20V 5 Ah batteries.

They have been sitting in their original packages since 2023.

You guessed it. 3/4 were fine, 1/4, DOA.

The good thing is I have the original invoice and these are legit (I also have ones from eBay that are likely counterfeit but have been in use since 2017 so no issues). Called DeWalt and they are sending a new replacement.

They wanted a pic of the battery showing date code (and I believe ser# even though they didn't say that), and the invoice. Covered for 3 years, and the warranty on the replacement lasts for the original warranty (just like Costco before people ripped them off).

There are some other batteries in the basement that I better check, not 5 Ah but smaller, that I never use.

I did buy eBay ones for half price and the packages look absolutely identical. Only stopped once I became aware of the high likelihood of counterfeit. But as mentioned, those eBay ones are 9 years old and still used daily. Kind of intersting that legit batteries, 1/4 did in fact fail from discharge.

p.s. just retrieved a 2017 5 Ah and it was perfectly good having not been charged in probably 5+ years, as well as 2 1.5 Ah never charged since 2022. Not sure what happened to the brand new 5 Ah. Guess the moral of the story is either charge everything every 6 mos, or don't have spares you don't need. I use the same 4 daily, not the others...

This is one of those projects that IMO are best left to a place like iFixit. I had a battery replaced recently that was $30 + parts so it came in around $70. What was interesting is it took 30 minutes and I got to watch. Of course iFixit has some specialized tool, one very unique thing is called an “anti-clamp” which is patented and improves on the Apple tool. They also have various picks for opening the case all with insertion depth markings.

I had two Samsung Galaxy phones that needed replacement batteries. I replaced the battery in the first one, but broke the glass back case in the process. No problem. I replaced the back cover. Heat the seals so the glue melts. Remove some screws. Ory off the old battery and disconnect the connector.
The speaker phone became very muffled after that. I did not know if something went wrong. I replaced the phone a few weeks later.
The battery went bad in my replacement phone, so I was more careful the second time. Now a few months later the phone likes to reboot frequently. The USB port on the phone seems flaky. The second time the battery caught fire when I tried to remove it. That was a little scary.

I have set my phone batteries to charge slowly, and not to charge to full capacity. The phone batteries like to swell up after a year. They get too big and crack open the case. Phone batteries do not last long.

Just acquired a new Samsung. How are you setting the phone not to charge to full capacity?

YouTube has DIY battery change videos for common smartphones and tablets. Depending on the device, it may not be for the inexperienced. I looked at it for an iPad that Apple wouldn't even touch anymore and decided, nope, not for me. Many devices are not designed for easy battery swaps.

Another concern, even if you think you're up to it, or even if you're paying somebody else to do it, is to be sure a recently manufactured lithium ion battery is going in and not a lithium ion battery that was made a two-plus years ago.

I dunno if all Samsungs are created equal, but on my S25+ it's Settings => Battery => Battery Protection => Maximum. There's a slider you can set to the max % battery charge you want to limit to.